/*	Copyright (c) 2008, MyBlock
	Author: Kristoffer Ahl, Spinit AB	*/

/* =TODO: Test and document browser compatibility */
/* =TODO: Add comments for variables, functions, methods etc */
/* =TODO: Implement custom events (onAbort, onTimeout etc) */
/* =TODO: Implement status notification events (Processing etc) */
/* =MB.Ajax */
MB.createNamespace("Ajax");
MB.Ajax = function() {
	/**
	 * @description Turns Ajax off. Used primarily for debug purposes.
	 * @property _ajax_off
	 * @private
	 * @static
	 * @type boolean
	*/
	var _ajax_off = MB.Config.Ajax.AjaxOff; // =TODO: Implement or remove
	
	/**
	 * @description Turns debug on. Used for debug purposes.
	 * @property _ajax_debug
	 * @private
	 * @static
	 * @type boolean
	*/
	var _ajax_debug = MB.Config.Ajax.AjaxDebug; // =TODO: Implement or remove
	
	/**
	 * @description Contains version data.
	 * @property _ajax_info
	 * @private
	 * @static
	 * @type string
	*/
	var _ajax_info = "MB-Ajax|0.1";
	
	/**
	 * @description Contains valid content-type headers.
	 * @property _content_types
	 * @private
	 * @static
	 * @type object
	*/
	var _content_types = {
		xml : "text/xml",
		html : "application/x-www-form-urlencoded" // =TODO: Change typename to text!?
	};
	
	var _timeout_handlers = {};
	var _poll_handlers = {};
	var _request_id = 0;
	
	var createResponseObject = function(xhr,callback) {
		var response = {}, content_type;
		/*	=TODO: Add response object properties response.type = (abort, timeout, complete)
			=TODO: Research content types and a better way to handle the response
		*/
		if (xhr && xhr.conn && xhr.options) {
			response.requestId = xhr.rId;
			content_type = xhr.conn.getResponseHeader("Content-Type");
			if (content_type && content_type.indexOf("text/html") >= 0) {
				response.data = xhr.conn.responseText;
			} else if (content_type && content_type.indexOf("application/xml")) {
				response.data = xhr.conn.responseXML;
			} else {
				if (xhr.conn.responseXML && xhr.conn.responseXML.nodeType === 9) {
					response.data = xhr.conn.responseXML;
				} else {
					response.data = xhr.conn.responseText;
				}
			}
			response.options = xhr.options;
		}
		return response;
	};
	
	var getXhrObject = function() {
		var xmlhttp, obj;
		if (window.XMLHttpRequest) {
			xmlhttp = new XMLHttpRequest();
			obj = { conn:xmlhttp, rId:_request_id };
		} else if(window.ActiveXObject) {
			try {
				xmlhttp = new ActiveXObject("Msxml2.XMLHTTP.4.0");
				obj = { conn:xmlhttp, rId:_request_id };
			} catch (e) {
				try {
					xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
					obj = { conn:xmlhttp, rId:_request_id };
				} catch (e2) {
					try {
						xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
						obj = { conn:xmlhttp, rId:_request_id };
					} catch (e3) {
						xmlhttp = null;
					}
				}
			}
		}
		if (obj && typeof obj.rId === "number" && isFinite(obj.rId)) {
			_request_id++;
		} else {
			obj = null;	
		}
		return obj;
	};
	
	var handleResponse = function(xhr,callback) {
		var conn_status, response;
		try
		{
			if (xhr.conn && xhr.conn.status !== undefined && xhr.conn.status !== 0) {
			 	conn_status = xhr.conn.status;
			} else {
				conn_status = 13030;
			}
		}
		catch(e){
			conn_status = 13030;
		}
		if (conn_status >= 200 || conn_status < 300 || conn_status === 1223) {
			response = createResponseObject(xhr,callback);
			
			if (xhr.isLoad) {
				// =TODO: Refactor -> function
				var options = xhr.options;
				if (options.target) {
					var target = options.target;
					if (typeof target !== "object" || !target.nodeType || target.nodeType !== 1) {
						target = document.getElementById(options.target);
					}
					if (target) {
						if (options.add) {
							target.innerHTML += response.data;
						} else {
							target.innerHTML = response.data;	
						}
					}
				}
			} else if (callback && callback.success) {
				callback.success(response);
			}
		} else {
			if (callback && callback.failure) {
				response = "Failure"; // =TODO: Implement createResponseObject method
				callback.failure(response);
			}
		}
		MB.Ajax.endRequest(xhr);
	};
	
	var setRequestHandlers = function(xhr,callback) {
		var timeout = xhr.options.timeout;
		var interval = xhr.options.poll;
		
		MB.Ajax.getTimoutHandlers[xhr.rId] = window.setTimeout(function() {
			MB.Ajax.abortRequest(xhr,callback);
		},timeout);
		
		MB.Ajax.getPollHandlers[xhr.rId] = window.setInterval(function() {
			if(xhr.conn && xhr.conn.readyState === 4){
				delete MB.Ajax.getPollHandlers[xhr.rId];
				handleResponse(xhr,callback);
			}
		},interval);

		return xhr;
	};
	
	var setRequestHeader = function(xhr) {
		if (xhr && xhr.options && xhr.conn) {
			var contentType = xhr.options.contentType;
			if (contentType) {
				xhr.conn.setRequestHeader("Content-Type", contentType);
			}
			var headers = xhr.options.requestHeaders;
			for (var key in headers) {
				xhr.conn.setRequestHeader(key, headers[key]);
			}
		}
		return xhr;
	};
	
	return {
		// =attachLoader, =Deprecated
		attachLoader : function(target,message,className,imageUrl,clearTarget,beforeTarget) {
			alert("MB.Ajax.attachLoader() is deprecated!");
			MB.UI.attachLoader(target,message,className,imageUrl,clearTarget,beforeTarget);
		},
	
		// =captureData
		captureData : function(elem) {
			var data = "", index, option, selected_values
			var data_elements = MB.getElementsByTagNames("input,select,textarea",elem);
			if (!data_elements) return false;
			for (var i=0; i<data_elements.length; i++) {
				element = data_elements[i], add = false;
				switch (element.type.toLowerCase()) {
					case "checkbox":
						if (element.checked) add = true;
						break;
					case "radio":
						if (element.checked) add = true;
						break;
					case "hidden":
					case "text":
					case "password":
						add = true;
						break;
					case "select-one":
						add = true;
						break;
					case "select-multiple":
						selected_values = "";
						for (index=0; index<element.options.length; index++) {
							option = element.options[index];
							if (option && option.selected) {
								if (selected_values.length>0) selected_values+= ",";
								selected_values+= escape(option.value);
							}
						}
						if (selected_values.length>0) {
							data+= (element.name + "=" + selected_values + "&");
						}
						break;
					default:
						break;
				}
				if (add) {
					data+= element.name;
					data+= "=";
					data+= encodeURI(element.value); // =TODO: Validate effects of using encodeURI instead of escape
					data+= "&";
				}
			}
			if (data.charAt(data.length-1) == "&") {
				data = data.substr(0,data.length-1);
			}
			if (data && data.length > 0) {
				return data;
			} else {
				return null;
			}
		},

		// =clearLoaders, =Deprecated
		clearLoaders : function(container) {
			alert("MB.Ajax.clearLoaders() is deprecated!");
			MB.UI.clearLoaders(container);
		},

		// =getContentType
		getContentType : function(v) {
			return _content_types[v];
		},
	
		// =getTimoutHandlers
		getTimoutHandlers : function() {
			return _timeout_handlers;	
		},
		
		// =getPollHandlers
		getPollHandlers : function() {
			return _poll_handlers;	
		},
		
		// =abortRequest
		abortRequest : function(xhr,callback) {
			if (xhr && xhr.conn) {
				xhr.conn.abort();
				MB.Ajax.endRequest(xhr);
			}
			if (callback && callback.failure) {
			    var response = MB.Config.Ajax.Aborted; // =TODO: Implement createResponseObject method
				callback.failure(response);	
			}
			return true;
		},
		
		// =beginRequest
		beginRequest : function(url,callback,options) {
			if (!url) return null;
			var xhr = getXhrObject();
			if (xhr) {
				xhr.options = options;
				if (!xhr.options) {
					xhr.options = new MB.Ajax.Options();
				}
				xhr.isLoad = (callback) ? false : true;
				xhr.conn.onreadystatechange = function () {};
				xhr.conn.abort(); // =TODO: Verify the need to abort
				xhr.conn.open(xhr.options.method.toUpperCase(),url,xhr.options.async);
				xhr = setRequestHeader(xhr);
				xhr = setRequestHandlers(xhr,callback);
				if (callback && callback.beginRequest) {
					callback.beginRequest(xhr); // =TODO: Implement as custom event
				}
				xhr.conn.send(options.postData);
				return xhr;
			} else {
				return null;	
			}
		},
		
		// =endRequest
		endRequest : function(xhr) {
			if (xhr && xhr.conn) {
				window.clearTimeout(MB.Ajax.getTimoutHandlers[xhr.rId]);
				delete MB.Ajax.getTimoutHandlers[xhr.rId];

				window.clearInterval(MB.Ajax.getPollHandlers[xhr.rId]);
				delete MB.Ajax.getPollHandlers[xhr.rId];
			
				xhr.conn = null;
				xhr = null;
			}
		},
		
		// =hijax
		hijax : function(elem,evt,callback,options) {
			var target = document.getElementById(elem);
			if (target) {
				// TODO: Implement "evt" argument
				target.onsubmit = function() {
					// =TODO: Important! Research better way to integrate validation
					var is_valid = (this.validation && this.validation.validate(this)) ? true : false;
					if (!is_valid) {
						return false;
					} else {
						var url = this.action;
						if (!options) {
							options = new MB.Ajax.Options();
						}
						if (this.method) {
							options.method = this.method.toUpperCase();
						} else {
							options.method = "POST";
						}
						options.postData = MB.Ajax.captureData(target);
						MB.Ajax.beginRequest(url,callback,options);
						return false;
					}
						
				}
			}
		},
		
		// =load
		load : function(elem,url,add,options) {
			if (!options) {
				options = new MB.Ajax.Options();
			}
			options.target = elem;
			options.add = (add) ? add : false;
			MB.Ajax.beginRequest(url,null,options);
		},
		
		// =Callback
		Callback : function(successHandler,failureHandler,beginRequestHandler) {
			return {
				beginRequest : ((beginRequestHandler) ? beginRequestHandler : null), // =TODO: Implement as custom event
				failure : ((failureHandler) ? failureHandler : null),
				success : ((successHandler) ? successHandler : null)
			};	
		},
		
		// =Options
		Options : function() {
			return {
				add : false,
				async : true,
				contentType : MB.Ajax.getContentType("html"),
				encoding : "UTF-8",
				method : "GET",
				poll : 50,
				postData : null,
				requestHeaders : { "X-Request-Type" : "Ajax", "X-Request-Framework" : _ajax_info },
				target : null,
				timeout : 10000
			};
		}
	};
}();

// =NOTE: Keep as dev-reference (=TODO:) but remove before release
//var successHandler = function(response) {
//	if (response && response.responseText) {
//		if (response.options && response.options.target) {
//			var target = document.getElementById(response.options.target);
//			if (target) target.innerHTML = response.responseText;
//		} else {
//			alert("Success: " + response.responseText);
//		}
//	}
//}
//var failureHandler = function(response) {
//	alert("Failure: " + response);
//}
//MB.addEvent(window,"load",function() {
//		var callback = new MB.Ajax.Callback(successHandler,failureHandler);
//		var options = new MB.Ajax.Options();
//		if (options) {
//			options.method = "post";
//			options.target = "Content-Area-Header";
//			options.contentType = MB.Ajax.getContentType("xml");
//			options.timeout = 3000;
//		}
//		var t = setTimeout(function() {
//			MB.Ajax.load(document.getElementById("Content-Area"),"http://localhost/MBBeta2/?ajax=1",true);
//		}, 3000);
//		MB.Ajax.beginRequest("http://localhost/ajax/resource_2.asp",callback,options);
//});